Wind power is considered one of the cleanest, most environmentally friendly energy sources presently available, and wind turbines have gained increased attention in this regard. A modern wind turbine typically includes a tower, generator, gearbox, nacelle, and one or more rotor blades. The rotor blades capture kinetic energy of wind using known foil principles. The rotor blades transmit the kinetic energy in the form of rotational energy so as to turn a shaft coupling the rotor blades to a gearbox, or if a gearbox is not used, directly to the generator. The generator then converts the mechanical energy to electrical energy that may be deployed to a utility grid.
The particular size of wind turbine rotor blades is a significant factor contributing to the overall efficiency of the wind turbine. Specifically, increases in the length or span of a rotor blade may generally lead to an overall increase in the energy production of a wind turbine. Accordingly, efforts to increase the size of rotor blades aid in the continuing growth of wind turbine technology and the adoption of wind energy as an alternative energy source. However, as rotor blade sizes increase, so do the loads transferred through the blades to other components of the wind turbine (e.g., the wind turbine hub and other components). For example, longer rotor blades result in higher loads due to the increased mass of the blades as well as the increased aerodynamic loads acting along the span of the blade. Such increased loads can be particularly problematic in high-speed wind conditions, as the loads transferred through the rotor blades may exceed the load-bearing capabilities of other wind turbine components.
Certain surface features, e.g. spoilers, may be utilized to separate the flow of air from the outer surface of a rotor blade, thereby reducing the lift generated by the blade and reducing the loads acting on the blade. Other surface features, e.g. vortex generators, may delay separation of the air flowing over a rotor blade to increase loads during periods of decreased wind. In many instances, both of these surface features are designed to be permanently disposed along the outer surface of the rotor blade. As such, the amount of lift generated by the rotor blade is reduced or increased regardless of the conditions in which the wind turbine is operating and does not allow for any dynamic control.
Alternatively, it is known in the art to provide one or more actuators within the rotor blade shell to move the surface features between the spoiler and vortex generator positions and/or between actuated and recessed positions within the blade shell. Such actuators, however, are installed within the rotor blade shell, thereby increasing maintenance and/or installation time and costs. In addition, such actuators can damage the rotor blade shell.
Accordingly, a rotor blade assembly having improved surface features that addresses the aforementioned issues would be welcomed in the technology.